In the last year, some 39,000 migrants, mostly from North Africa, tried to make their way to the United Kingdom from the French port of Calais by boarding trucks and trains crossing the English Channel. In response, the British government attempted to secure the entrance to the tunnel in Calais, dispatching two and a half miles of security fencing that had been used for the 2012 Olympics and the 2014 NATO summit.

The United Kingdom’s improvised response to the migrant crisis, with recycled fences substituting for a coherent immigration policy, is emblematic of its increasingly parochial approach to the world beyond its shores. The Conservative government of Prime Minister David Cameron appears to lack a clear vision of the country’s place on the global stage. The United Kingdom, a nuclear power and permanent member of the UN Security Council, now seems intent not on engaging with the outside world but on insulating itself from it. The United Kingdom does not merely lack a grand strategy. It lacks any kind of clearly defined foreign policy at all, beyond a narrow trade agenda.

Historically, the United Kingdom has been an active player in world politics. After the loss of its empire, the country was a founding and engaged member of the institutions of the postwar Western order. British governments have led the way in pressing for, and undertaking, humanitarian interventions from Sierra Leone to Kosovo. And the United Kingdom’s relationship with the United States has been a great asset to both sides since World War II.

Recently, however, factors including fatigue following the wars in Afghanistan and Iraq, a recession, and a prime minister with little apparent interest in foreign affairs have conspired to render the British increasingly insular. The British diplomatic corps and military have seen their capabilities slashed amid harsh austerity measures. In its limited contribution to the campaign against the self-proclaimed Islamic State (also known as ISIS), in its mercantilist approach to China, and in its inability to formulate a